(a) Field of the Invention
The present invention relates to a balance shaft module equipped with a hydraulic pump, particularly to a balance shaft module in which a hydraulic pump is formed as one body and thus a number of elements thereof are reduced to reduce cost.
(b) Description of the Related Art
All four-stroke reciprocating engines perform ignition at regular intervals to reduce vibrations of the engine. When a crank shaft of the engine rotates 720°, one cycle is completed, and ignition is performed at 180° intervals in an inline four-cylinder reciprocating engine. That is, when the crank shaft is rotated 180°, power is generated twice such that a second vibration occurs, which is more than a three cylinder or V-type engine. Therefore, two balance shafts that rotate in opposite directions and twice as fast as the crank shaft are required so as to reduce the second vibration.
The balance shaft module used for the inline four-cylinder engine reduces the second vibration of the engine. The balance shaft module is provided on the cylinder block or at a lower portion of the crank shaft adjacent to an oil pan of the engine.
The balance shaft module is composed of two shafts, and a driving sprocket is provided in one of the shafts. The driving sprocket is connected to the crank shaft by a gear or a chain. Further, the two shafts are connected by helical gears, and the two shafts rotate in opposite directions by way of the helical gears. Balance weights are respectively provided to the two shafts of the balance shaft module.
However, since in conventional arts, the balance shaft module and a hydraulic pump are separately provided, a number of parts of an engine and a manufacturing cost increase. In addition, there is a problem that noise and vibration occur when gears of the balance shaft are rotating in a meshed situation.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.